“Gastric pneumatosis , also referred to as gastric emphysema or emphysematous gastritis, is the least common site of pneumatosis within the gastrointestinal tract, seen in 9% of cases in a single review of 86 patients with gastrointestinal pneumatosis on CT. The term gastric pneumatosis encompasses both gastric emphysema and emphysematous gastritis, with the latter referring specifically to the uncommon, though life-threatening, infectious variant. Dependent tiny locules or linear collections of gas within the dependent gastric wall raise concern for pneumatosis, though gas within the rugae may mimic true pneumatosis. Correlation with sagittal and coronal reconstructions as well as persistence between arterial and portal venous phases may aid in diagnosis.”

“While gastritis may diffusely involve the stomach, focal, and segmental thickening can alternatively be seen, particularly in the setting of Helicobacter pylori infection or with medications such as nonsteroidal anti-inflammatory drugs (NSAIDs). NSAID-induced gastritis occurs secondary to decreased prostaglandin synthesis, resulting in decreased mucus and bicarbonate secretion with subsequent gastric injury. Focal gastritis or ulcers secondary to NSAIDs or other medications classically occur along the gastric body and antrum along the greater curvature due to their dependent position. Focal wall thickening may mimic neoplasm; due to the overlap between MDCT appearance and gastric neoplasm, endoscopy is often required for definitive diagnosis.”

“Gastric ulcers are common and often result from H. pylori infection or medications, especially NSAIDs. Superficial ulcers are not typically well visualized on MDCT; however, deep or penetrative ulcers may be appreciated. Secondary inflammation can result in adjacent wall thickening or other soft tissue change. Extraluminal gas or pneumoperitoneum may be present in cases of perforation.”

“Upper gastrointestinal bleeding accounts for approximately 0.1% of hospitalizations in the USA each year, with a mortality rate of 10%. Common causes of gastric hemorrhage include ulcers, varices, Mallory– Weiss tears, vascular lesions, and neoplasms. Clinical presentation varies depending on the degree of blood loss, ranging from asymptomatic with less than 00 mL/day to systemic shock if greater than 15% of the circulating blood volume is lost. Contrast-enhanced MDCT may allow direct visualization of the bleeding site via high-attenuating contrast extravasation. In the absence of contrast, high-attenuating debris within the stomach fundus can suggest ongoing or prior hemorrhage, particularly in hospitalized patients without recent ingestion with unexplained anemia or abdominal pain.”

“Although uncommon, foreign body ingestion may result in dramatic imaging findings. Foreign body ingestions are most common in children, the intellectually disabled, and individuals with predisposing factors or injurious situational problems (e.g., suicidal ideation, anxiety, alcohol abuse, etc.). Clinical history is critical and MDCT is often performed to exclude complications. The vast majority of objects pass through the gastrointestinal tract without issue. Elongate or sharp objects have increased risk of perforation or obstruction. Secondary complications including mediastinitis, peritonitis, abscess formation, or sepsis may occur following perforation. High-risk objects including sharp or large foreign bodies may require endoscopic or surgical removal.”

“Unlike the majority of gastrointestinal fistulae, which are often iatrogenic or related to inflammatory bowel disease, gastrocolic fistulae are most commonly caused by penetrating benign ulcers in the setting of NSAID use. Neoplasm and inflammation are less common causes. Classically patients present with acute halitosis, feculent vomiting, and undigested food, though the most common clinical presentation is nonspecific abdominal pain.”

“Most commonly seen in elderly women with a history of biliary disease, gallstone-associated gastric outlet obstruction—or ‘‘Bouveret’s Syndrome’’—is a rare condition caused by retrograde passage of a large gallstone into the duodenum or stomach with subsequent obstruction. Although the least common location for gallstones to become lodged, early recognition or duodenal or gastric gallstone obstruction is critical due to a reported mortality of 30%. MDCT or radiographs may aid in the diagnosis prior to invasive assessment through visualization of the gallstone or secondary features including pneumobilia and gastric distension; however, endoscopy is diagnostic. As with the related condition of gallstone ileus, management is surgical.”

“The term gastric volvulus implies at least 180° rotation of the stomach and gastric outlet obstruction. Coronal reformatted images are particularly helpful in diagnosing gastric volvulus and often show these findings to greater advantage than axial images alone. Organoaxial or mesenteroaxial rotation of the stomach alone does not define volvulus.”

“Therefore, the degree of distention determines the thickness of the normal gastric wall and folds. In an adequately distended stomach, the normal nondependent gastric body is less than or equal to 5 mm in thickness. The antral wall, in contrast, may normally measure less than or equal to 12 mm in thickness.”

“Inadequate gastric distention limits diagnostic evaluation of the stomach and poses a potential pitfall, as it may create a false appearance of thickening or, conversely, may obscure true disease. When evaluating abnormal gastric wall thickening in a nondistended stomach, supplementary findings can be helpful in identifying disease. Findings that should raise suspicion for gastric disease include focal or ec- centric gastric wall thickening, low attenuation or nodularity of the gastric wall, mucosal hyper- enhancement, and adjacent fat stranding.”

“Gastritis, or gastric mucosal inflamma- tion, is a common condition that often results in submucosal edema and hyperplasia of the gastric mucosa . Gastritis is most frequently secondary to Helicobacterpylori infection, nonsteroidal anti-inflammatory drugs (NSAIDs), alcohol, or systemic illness. Patients with gastritis may present with epigastric pain, nausea, vomiting, or loss of appetite. ”

“The combination of mucosal hyperemia with submucosal edema results in the appearance described as mural stratification, which is most pronounced at arterial phase imaging. Gastritis may be focal, segmental, or diffuse. Gastritis due to H pylori infection can have a variety of manifestations, including circumferential antral wall thickening and focal thickening along the greater curvature.”

“Emphysematous gastritis is an uncommon condition with a high mortality rate and is caused by mucosal disruption and invasion of microorganisms into the gastric wall, producing intramural gas. Causative microorganisms reported in the literature include both aerobic and anaerobic bacteria as well as fungal species. Frequently isolated organisms include Escherichia coli, Klebsiella pneumoniae, Enterobacter species, Pseudomonas aeruginosa, and Candida species”

“Air in the gastric wall can be seen in a benign form of gastric emphysema, which can be encountered in the setting of a recent procedure and is typically asymptomatic. Patients with benign gastric emphysema demonstrate few clinical symptoms, whereas emphysematous gastritis causes patients to present with severe pain and potentially with sepsis and shock. ”

“Volvulus occurs most often in elderly patients with a hiatal hernia and may be acute or chronic-recurrent. Paraesophageal hernias, particularly large type III hernias, are at greater risk of gastric volvulu. Because of the potential for ischemia and perforation, acute gastric volvulus has high morbidity and mortality if not treated rapidly with decompression of the stomach, reduction of the volvulus, and correction of the underlying cause. ”

“Gastric volvulus is divided into two subtypes, organoaxial and mesenteroaxial, based on the axis of rotation. Organoaxial volvulus is obstruction of the stomach due to rotation around the long axis of the stomach, resulting in the antrum moving anterosuperiorly and the fundus rotating posteroinferiorly, so that the greater curvature lies superior to the lesser curvature. In mesenteroaxial volvulus, the stomach rotates around its short axis, such that the antrum moves above the gastroesophageal junction, twisting its vascular supply. ”

“Organoaxial volvulus is more common than mesenteroaxial volvulus, accounting for approximately two-thirds of cases, and is commonly associated with congenital and acquired diaphragmatic defects. Many cases may have overlapping features of organoaxial and mes- enteroaxial volvulus and indeed may be due to a combination of these two entities. ”

“Perforation is the most common complication of PUD. Ulcers on the anterior wall and curvatures perforate freelyinto the peritoneal space; posterior ulcers may perforate into the lesser sac and can be relatively contained. Findings at CT may include the features of gastric ulcers discussed previously in combination with free intraperitoneal fluid or gas, extraluminal oral contrast material, and wall discontinuity. Ulcers are more likely to be detected at CT when they perforate, because the defect is transmural and because extraluminal gas and fluid may accumulate at the site of perforation. ”

“Gastric perforation can also occur with a gastric malignancy, particularly in ulcerated masses such as those seen with adenocarcinoma, lymphoma, and large gastrointestinal stromal tumors (GISTs). Perforation from gastric adenocarcinoma typically occurs in patients more than 65 years of age with advanced stage disease. In patients with lower stage disease, a focal ulcerated mass can perforate if the ulceration is deep. ”

“Gastric hemorrhage can be seen in a variety of gastric diseases, including PUD, tumor, varices, gastritis, and arteriovenous malformations. Patient presentation is variable, ranging from asymptomatic to hypovolemic shock. Direct signs of bleeding include hematemesis, coffee-ground emesis, melena, or, in the setting of rapid bleeding, hematochezia. Although endoscopy is the preferred method of diagnosing and treating upper gastrointestinal bleeding, CT is useful in cases where endoscopy is not clinically feasible or is nondiagnostic.”

“CT findings of gastric hemorrhage include intraluminal contrast blush from active bleeding or hyperattenuating clot from recent bleeding. Clots in these cases are often seen in the fundus, which is the most dependent location in the supine patient. The location of the highest- attenuation clot (the sentinel clot) can indicate the source of bleeding.”

“Hyperattenuating material in the stomach, including ingested material such as residual contrast medium or medications, surgical material, or foreign bodies, can potentially result in both false-positive and false-negative studies by mimicking or obscuring bleeding. Obtaining a non- contrast scan can avoid this imaging pitfall. Even in the absence of active bleeding, CT may be helpful in identifying the underlying culprit.”

“Gastric ischemia is an uncommon condition caused by diffuse or focal vascular insufficiency. Although the extensive collateral blood supply to the stomach is protective, systemic hypoten- sion (as is seen in sepsis or shock) may result in gastric ischemia. Other described causes of gastric ischemia include celiac and mesenteric stenosis, vasculitis, and disseminated thrombo- embolism.”

“Imaging findings in gastric ischemia range from focal ulceration to gastric wall thickening to intramural gas. Ischemic ulcerations most commonly occur along the anterior and posterior gastric walls near the anastomoses between the two arterial arches over the lesser and greater curvatures. Gastric dilatation may also be seen and is thought to be due to ischemic gastroparesis .”